Wide-band vertically polarized omnidirectional antenna

ABSTRACT

A wide-band vertically polarized omnidirectional antenna consists of an outer first cylindrically-shaped metal surface with a second cylindrically-shaped metal surface coaxial with and located within the first metal surface and concentrically disposed about a third cylindrically-shaped metal surface. The first metal surface is formed of individual antenna elements each having a ring of circumferentially extending slots spaced axially from the ends of the elements with adjacent elements spaced apart by a circumferential ring slot. Alternatively, the first metal surface can be a continuous tubular member divided in the axial direction by a number of axially spaced rings of circumferentially extending slots. Each ring of slots consists of a number of uniformly circumferentially spaced rectangularlyshaped slots. A three-wire line is associated with each ring of slots with two of the wires extending circumferentially while the third or inner wire extends radially inwardly from the first metal surface through the second metal surface in contact-free relationship and then into contact with the third metal surface.

United States Patent [1 1 Tymann [111 3,871,000 [451 Mar. 11, 1975WIDE-BAND VERTICALLY POLARIZED OMNIDIRECTIONAL ANTENNA [75] Inventor:Gerhard Tymann, Unterhaching,

Germany [73] Assignee: Messerschmitt-Bolkow-Blohm Gesellschaft MitBeschrankter Hoftung, Munich, Qermany [22] Filed: Nov. 30, 1973 [21]Appl. N0.: 420,581

[30] Foreign Application Priority Data Dec. 2. 1972 Germany 2259082 [52]U.S. Cl. 343/771, 343/791 [51] Int. Cl. H0lq 13/10 [58] Field of Search343/769, 770, 771, 791- [56] References Cited UNITED STATES PATENTS2,973,515 2/1961 Adams 343/790 3,417,400 12/1968 Black 343/771 PrimaryE.\'aminerEli Lieberman Attorney, Agent, or Firm-Toren, McGeady andStanger "Ill [57] ABSTRACT A wide-band vertically polarizedomnidirectional antenna consists of an outer first cylindrically-shapedmetal surface with a second cylindrically-shaped metal surface coaxialwith and located within the first metal surface and concentricallydisposed about a third cylindrically-shaped metal surface. The firstmetal surface is formed of individual antenna elements each having aring of circumferentially extending slots spaced axially from the endsof the elements with adjacent elements spaced apart by a circumferentialring slot. Alternatively, the first metal surface can be a continuoustubular member divided in the axial direction by a number of axiallyspaced rings of circumferentially extending slots. Each ring of slotsconsists of a number of uniformly circumferentially spacedrectangularly-shaped slots. A three-wire line is associated with eachring of slots with two of the wires extending circumferentially whilethe third or inner wire extends radially inwardly from the first metalsurface through the second metal surface in contact-free relationshipand then into contact with the third metal surface.

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WIDE-BAND VERTICALLY POLARIZED OMNIDIRECTIONAL ANTENNA SUMMARY OF THEINVENTION The present invention is directed to a wideband, verticallypolarized omnidirectional antenna and, more particularly, it concernsthe arrangement of such antenna and especially its outer surface whichis formed of a hollow cylindrical metal surface divided bycircumferentially extending rings of slots located in planes extendingperpendicular to the axis of the metal surface. The rings of slots arearranged to divide the first surface into hollow cylinders having aheight or axial length of about A to A of the wavelengths. A three-wireline feeds each of the ring slots and a second hollowcylindrically-shaped metal surface disposed inwardly of and coaxiallywith the first metal surface serves as a meter frame or support.

For certain uses, for example, in space travel, antennas with a goodcircular radiation pattern or characteristic are required in a planewith medium gain. In addition to high mechanical stability, the abilityto withstand extremely high temperature stresses from about 80C to +200Cis required in many space probes, for example, in solar probes.Frequently the antenna dimensions, particularly the diameter, are given.In many satellites, several antennas must be superposed with amagnetometer arranged at the end of the antenna arm. The necessary feedlines for the upper antennas and for the magnetometer must be arrangedwithin the interior of the lower antennas.

To meet these requirements it has been known to use slot radiators whichconsist of two coaxial hollow cylindrical metal surfaces where the outermetal surface contains a circumferentially extending ringslot located ina plane disposed perpendicularly to the axis of the metal surface. Insuch an arrangement the inner metal surface serves as a meter frame orsupport. Two hollow cylindrical rings separated by a ring slot form aslot radiator element. For focusing the radiation in a planeperpendicular to the axis of the elements, several of the elements aresuperposed coaxially to form a collinear system, with the innercontinuous hollow cylindrical metal surface serving as a commonsupporting tube (see DOS, 1,441,614; Jasik Antenna Engineering Handbook,McGraw-I-Iill Book Company, New York, 1961, pages 26-2 to 26-4, andSilvers Microwave Antenna Theory and Design, McGraw-Hill Book Company,New York, 1949, page 309). In the wide-band omnidirectional antenna withvertical polarization describedv in the above patent, the distancebetween two slot radiator elements is about one wavelength, and thedistance between the inner and outer hollow cylindrical metal surfacesis 0.2-0.12 wavelengths. The outer hollow cylindrical surface is securedover narrow stirrups on the inner hollow cylindrical metal surface. Theomnidirectional antennas mentioned in the two publications use the twoouter conductors of the three-wire symmetrization to maintainthedistance of the outer hollow cylinders. These known omnidirectionalantennas do not meet, however, the mechanical stability requirements forair and space travel. Reinforcement of the supports is not possiblewithout, at the same time, impairing the electrical properties of theomnidirectional antenna.

The installation of a toriodal dielectric to increase the mechanicalstrength also has disadvantages. For

space probes, for example, for a solar probe, a low-loss dielectric mustbe found which can withstand at least 200C. Further, it is verydifficult, particularly with regard to thermal and mechanical stresses,to obtain good contact'between the dielectric and the metal surface.When large temperature fluctuations occur, an air gap develops due tothe different coefficients of expansion of the metal and dielectric.Since the electrical field strength in the air gap is higher than in thedielectric, a breakdown may occur. Moreover, the antenna becomes highlyfrequency-sensitive, particularly in the form of a coaxial line radiator(note the Silver publication mentioned above).

The mounting of the hollow cylindrically-shaped rings with a constantslot width over the entire slot ring presents certain difficulties. Anychange of the generally very narrow slot or eccentricity of the hollowcylindrically-shaped ring results in considerable differences in theradiation and impedance diagrams.

The omnidirectional antenna described in the abovementioned patent isfed over two-wire lines arranged within hollow cylindrically-shapedrings. With many feeding points and several ring slots, such a systembecomes very complicated and unwieldy, particularly since impedanceconverters and concentrated blind elements must be inserted into thefeeding line system.

In the omnidirectional antennas described in the two publications, thespace within the second hollow cylindrically-shaped metal surfaces isdesigned as a tubular or coaxial conductor. The high-frequency energy isuncoupled over probes and is fed to the ring slots. To assure that awave can be excited at a given frequency, the tubular conductor musthave a corresponding diameter. In the design of the coaxial conductor, acertain diameter ratio of the outer to the inner conductor must bemaintained in view of wave resistance. If the diameter of the innerconductor is selected at a dimension such that a foreign cable can belaid within its interior, the diameter of the antennais frequently toogreat in respect to the wavelengths. In any case, it is not possible toarrange thicker supply lines for components arranged above theomnidirectional antenna inside the hollow cylindrically-shaped metalsurfaces in the proximity of the antenna axis.

If the diameter of the omnidirectional antenna is great compared to itswavelength, the use of ring slots with discrete feeding results in alack of symmetry in the radiation diagram. With ring slots, theradiation diagram can be influenced in the azimuth only by the number ofcoupling points and the diameter of the omnidirectional signal. Further,wide-band coupling of the ring slots is hardly possible.

Therefore, the primary object of the present invention is to provide anantenna with a good circular radiation characteristic in a plane and ofgreat band width, where the quality of the circular radiation is, forall practical purposes, independent of the diameter of the antenna andwhere the antenna has both high mechanical and thermal strength witheasy mountability and a simple and insensitive feeding system. Further,the arrangement of the antenna permits the placement of additionalsupply cables inside the antenna structure particularly in the proximityof its axis.

Accordingly, the problems experienced in the past are solved in thepresent invention by dividing the ring slot in a uniform manner intoindividual or separate circumferentially extending slots spaced apart inthe circumferential direction. Further, the individual slots can have arectangular form or they can be widened conically or in steps, or theycan be arranged as dumbbellshaped slots and each individual slot is fedover a threewire line from one or more coaxial conductors, and, ifnecessary, a third hollow cylindrically-shaped metal surface is providedinwardly of the first and second such surfaces. The second and thirdhollow cylindrically-shaped surfaces are designed as a feeding systemfor the antenna arrangement and the inner wires or conductors of thethree-wire line pass inwardly from the first metal surface incontact-free relationship through bores in the second metal surface andare coupled capacitatively or galvanically with the third metal surface.

Concentration of the radiation in a plane through the system axis isachieved by providing a ring of individual slots in an omnidirectionalradiator element so that two hollow cylinder rings are formed and byarranging several such omnidirectional radiator elements, whose heightis about equal to half the mean operating wavelength, in a superposedcoaxially arranged group with the individual radiator elements spacedapart in the axial direction by a circumferential ring slot.

In another arrangement of the first or outer hollow cylindrically-shapedmetal surface, the omnidirectional radiator elements are joined togetherin the form of a continuous tubular member provided with the individualinterrupted ring slots but without the separating circumferential ringslots.

The feeding or supply, which is not limited to the antenna according tothe present invention, is effected in the wide-band model in such a waythat at least one coaxial conductor is positioned within the thirdhollow cylindrically-shaped metal surface and acts as a coaxial feedconductor with the outer wire of the feed conductor conductivelyconnected to the third metal surface and with its inner conductorconductively connected to the second metal surface.

To be able to mount the feed or supply in an assembled antenna in asimple manner from the exterior of the antenna, and to obtain otheradvantages, the feed arrangement is laid out so that the coaxialconnection to the feed is arranged in the center of the antennastructure with the outer wire of the coaxial feed conductor conductivelyconnected to the third hollow cylindrically-shaped metal surface over ahollow cylinder extension extended through an opening in the third metalsurface and attached to it by a through connection and with the innerwire of the coaxial feed conductor passing outwardly through the hollowcylinder extension within another cylindrically-shaped member andattached to the exterior of the second metal surface. Further, anadjustable and fixable short-circuit plane is provided at the free endof the coaxial feed conductor at a distance of about $41 of the meanoperating wavelength for adjusting the amplitude and phase conditions inthe coaxial feed conductor.

By virtue of the present invention, it is possible to obtain a goodcircular radiation characteristic in a plane which is, to a greatextent, independent of the ratio of the antenna diameter to thewavelength. By using individual spaced slots in the interrupted ring ofslots and by using different geometric forms for the slots, it ispossible to obtain optimum wide-band matching. Furthermore, the symmetryof the arrangement can be improved, if necessary, by varying the lengthsof the single or individual slots, or a designed asymmetry can beproduced in the radiation pattern. By virtue of the single slots and theuse of larger antenna diameters, which is possible because of theindependence of the quality of the circular radiation characteristicfrom the antenna diameter/wavelength ratio, a very high mechanicalstrength is obtained, particularly in the design which does not useseparating ring slots between individual radiator elements. By employingthe continuous outer hollow cylindrically-shaped metal surface a furtherstiffening effect is obtained. Due to the feeding arrangement providedin the present invention, additional cables for other uses can bepositioned within the antenna structure close to its axis and at thesame time, a wide-band cabling can be effected which is accessible fromthe exterior even after the final mounting of the antenna. Interferenceimpedances producedby probes or other connecting pieces can becompensated partly by short-circuit planes at both ends of theomnidirectional antenna between the second and third hollowcylindrically-shaped metal surfaces. Since no dielectric is used, theantenna has a high thermal strength. Further, all atmospheric chargesare positively led off, since all parts of the antenna are grounded. Itis also possible to feed the omnidirectional antenna without the use ofthe third hollow cylindrically-shaped surface by using a tubularconductor arrangement. Further, the third metal surface could be used asan outer wire of a coaxial feed line. However, the advantages ofwideband cabling and of incorporating other cables close to the axis ofthe antenna would not be available.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which there are illustrated and described preferredembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1a is a partial view, partly in section, of an omnidirectionalantenna embodying the present invention, and incorporating radiatorelements having a length of about one-half the wavelength;

FIG. lb is a view similar to FIG. la, embodying the present inventionwith a continuous outer hollow cylindrically-shaped metal surface inplace of the individual radiator elements;

FIG. 2 is an enlarged sectional view showing the feeding arrangement forthe antenna; and

FIG. 3a to 30 show possible forms of the individual slots.

DETAILED DESCRIPTION OF THE INVENTION In FIG. la an omnidirectionalantenna is illustrated with its outer surface formed of a plurality ofcollinear radiator elements 12 each having a height or axial length ofabout 5% the wavelength. The individual radiator elements 12 are spacedapart in the axial direction of the antenna by circumferentiallyextending slots 3 formed between adjacent ends of the elements.Intermediate the ends of each element in a plane extendingperpendicularly of the axis of the antenna, an interrupted ring ofrectangularly shaped individual slots 4 extend in the circumferentialdirection of the elements.

Each individual slot 4 is fed over a three-wire line 5, 8, 9. The outerwires 8, 9 of the three-wire line serve to maintain the distance of theelements 12 from a radially inner hollow cylindrically-shaped metalsurface which is arranged coaxially with the radiator elements. Further,a third hollow cylindrically-shaped metal surface 14 is locatedcoaxially within the second metal surface 10. Each inner wire 5 of thethree-wire line is connected at its radially outer end to a nose 7 whichprotrudes in the axial direction from the surface of the radiatorelement 12 into the slot 4. Bores are formed in the second hollow metalsurface 10 so that each of the inner wires 5 passes inwardly through thebore in contact-free relationship from the second metal surface 10 andis conductively connected'to the third metal surface 14.

In FIG.'lb another embodiment of the omnidirectional antenna isillustrated which has the same design as shown in FIG. 1a. However,instead of the individual radiator elements 12 of FIG. la, in FIG. 1bthe radiator elements 12 are formed in a continuous tubular metalsurface 2 in which the rows of individual slots 4 extendingcircumferentially about the tubular member 2 are spaced apart at aboutthe mean operating wavelength.

In FIG. 2 a feeding arrangement for the invention is illustrated. Asshown, the coaxial conductor 16 opens into an outer cylinder 20 whichforms'a coaxial conductor together with an inner conductor member 21which is connected to the conductor 16. The outer wire of the coaxialconductor 16 is conductively connected with the hollow cylinder 20- andits inner wire is conductively connected with the inner conductor member21. The hollow cylinder is disposed tangentially to the inner surface ofthe third hollow metal surface 14. A hollow cylindrical extension 23extends normally to the axis of the hollow cylinder and outwardly fromit passing through an opening in the third metal surface 14 and it issecured by a screw conductor 24 to the outside surface of the thirdmetal surface 14. Spaced inwardly from the hollow cylindrical extension23 is another extension 26 provided with a female thread into which ascrew connector 31 is fitted for providing contact with the innerconductor member 21. The screw connector is mounted within a steppedhollow cylinder 27 having a narrow portion which extends through theextension 23 and a wider hollow cylindrical portion 28 which extendsthrough the. second metal surfacev 10 and has a flange 29'extendinglaterally over the outer surface of the metal surface 10 so that theflange can be connected by screw members to the metal surface 10.Accordingly, the outer conductor provided by the hollow cylinder 20 isconnected to the third metal surface 14 while the inner conductor 21 isconnected to the second metal surface 10 with the surfaces of theconnection disposed in spaced relationship. At a distance of about'% ofthe mean operating wavelength, an adjustable and fixable short-circuitplane is arranged in the innermost coaxial conductor to compensate oradjust the amplitude and phase conditions within the feed arrangement.

The outermost hollow cylindrically-shaped metal surface 2, that is theradiator elements 12, contains the slot radiators which radiate avertically polarized electromagnetic wave. The next inner hollowcylindrical metal surface 10 serves as a meter frame or support as wellas an outer wire for the coaxial feed system of the antenna arrangementand as a reflector. The inner wire of the coaxial feed conductor is incontact with this second metal surface 10. The innermost hollowcylindrically-shaped metal surface 14 forms the inner wire for thecoaxial feed system and it is connected with the outer wire of thecoaxial feed conductor.

Coaxial cable 15 shown in FIG. la-is provided to feed an external loadmounted above the antenna.

FIG. 3a shows an individual slot, which widens conically and FIG. 3b anindividual slot, which widens in steps. FIG. 3c shows an individual slotwith dumbbelllike shape. In the middle of the axial length of thisdumbbell-like shaped slot 4" a projection extends into the slot.

Without departing from the concept of the invention, the omnidirectionalantenna according to the invention can also be designed for horizontalpolarization.

The feeding device disclosed above is not limited to antennas of thetype described herein, it also applies generally to individual radiatorelements or radiator groups.

Preferred applications of the omnidirectional antenna according to theinvention are for air and space travel, as well as in mobile andstationary telemetry stations. The omnidirectional antenna described isparticularly suitable for the superposition of several antennas. Anotheradvantageous application of the antenna of the present invention is as aprimary radiator for reflection antennas, particularly forcylindrical-parabolic antennas.

The wide-band vertically polarized omnidirectional antenna has awavelength of about 5,5 inches. Typical diameter dimensions of thefirst, second and third hollow cylindrically-shaped metal surfaces wouldbe as follows: 3, 1,5 inches and 1 inch. Based on the above wavelengths,the axial lengths of the antenna elements 12 would be 0,45 wavelengths.Similary, based on the above wavelengths, the spacing between theinterrupted rings of slots 4 in FIG. 1b would be of the wavelength.

I claim:

1. A wide-band vertically polarized omnidirectional antenna comprisingafirst hollow cylindrically-shaped metal surface divided transversely ofits axis by a circumferentially extending slot into at least two hollowcylindrically-shaped rings having an axial length of $41 or k ofthewavelength, three-wire lines distributed uniformly over thecircumference of said first metal surface for feeding said slots, and asecond hollow cylindrically-shaped metal surface arranged within andcoaxially with said first metal surface as a support, wherein theimprovement comprises that said slot is formed of a plurality ofcircumferentially extending individual slots uniformly spaced apart inthecircumferential direction and forming a circumferentially extendinginterrupted ring slot, one said three-wire line for feeding each saidindividual slot, at least one coaxial conductor positioned within saidsecond metal surface, said second metal surface and said coaxialconductor arranged as a coaxial feeder system, said three-wire linecomprising inner wires extending radially inwardly from said first metalsurface, said second metal surface having bores therethrough alignedwith said inner wires so that said inner wires pass contact-free throughsaid second metal surface and are coupled capacitatively or galvanicallywith said coaxial conductor.

2. A wide-band vertically polarized omnidirectional antenna, as setforth in claim 1, wherein a third hollow cylindrically shaped, metalsurface is positioned within said second metal surface, said third metalsurface comprising one or several coaxial conductors in order to feedthe antenna system and, if necessary, comprising also other conductorsand feed lines not used for feeding the antenna system, said secondmetal surface and said third metal surface arranged as a coaxial feedersystem of the antenna, said three-wive line comprising inner wiresextending radially inwardly from said first metal surface, said secondmetal surface having bores therethrough aligned with said inner wives sothat said inner wives pass contact-free through said second metalsurface and are coupled capacitatively or galvanically with said thirdmetal surface.

3. A wide-band vertically polarized omnidirectional antenna, as setforth in claim 1, wherein said individual slots are rectangular in form.

4. A wide-band vertically polarized omnidirectional antenna, as setforth in claim 3, wherein a projection on said first hollowcylindrically-shaped metal surface extends into said rectangularlyshaped slot from one side thereof and is spaced from the other sidethereof, and one said inner wire of said three-wire line being coupledwith said projection into said slot.

5. A wide-band vertically polarized omnidirectional antenna, as setforth in claim 1, wherein said individual slots have conically wideningconfiguration.

6. A wide-band vertically polarized omnidirectional antenna, as setforth in claim 1, wherein said individual slots widen in a step-wisemanner.

7. A wide-band vertically polarized omnidirectional antenna, as setforth in claim 1, wherein said individual slots have a dumbbell-likeshape.

8. A wide-band vertically polarized omnidirectional antenna, as setforth in claim 7, wherein a projection on said first hollowcylindrically-shyped metal surface extends into said dumbbell-likeshaped slot from one side thereof and is spaced from the other sidethereof, and one said inner wire of said three-wire line being coupledwith said projection into said slot.

9. A. wide-band vertically polarized omnidirectional antenna, as setforth in claim 1, wherein said first metal surface comprises a pluralityof cylindrically-shaped omnidirectional antenna elements arranged insurface alignment, each said antenna element having an axial lengthabout equal to half the mean operating wavelength, said antenna elementsbeing spaced apart in the axial direction and forming a continuouscircumferentially extending slot therebetween, and each said antennaelement having said interrupted ring slot therein positioned axiallyfrom and intermediate its opposite ends.

10. A wide-band vertically polarized omnidirectional antenna, as setforth in claim 1, wherein said first metal surface comprises acontinuous axially elongated tubular member having a plurality ofaxially spaced said interrupted ring slots therein dividing said tubularmember into a plurality of interconnected omnidirectional antennaelements.

11. A wide-band vertically polarized omnidirectional antenna, as setforth in claim 2, wherein at least a part of oneof said coaxialconductors comprises an axially elongated hollow cylinder forming anouter conductor and an axially elongated inner conductor positionedcoaxially within and spaced inwardly from said hollow cylinder, saidhollow cylinder connected conductively to said third metal surface andsaid inner conductor connected conductively to said second metalsurface.

12. A- wide-band vertically polarized omnidirectional antenna, as setforth in claim 11, wherein said hollow cylinder forming the outerconductor is in surface contact with the surface of said third metalsurface and said third metal surface having an opening therethrough,said hollow cylinder having a tubular-shaped extension secured theretoand extending laterally outwardly therefrom transversely of the axialdirection of said hollow cylinder through the opening in said thirdmetal surface, a threaded connector member in screwed engagement withthe outer surface of said extension for fixing said hollow cylinder tosaid third metal surface, said second metal surface having an openingtherethrough aligned with the opening in said third metal surface, ahollow cylindrically-shaped member secured to the outer surface of saidsecond metal surface and extending through the opening in said secondmetal surface and through said tubularshaped extension secured to saidhollow cylinder and in spaced relationship to said tubular-shapedextension, and a connector member displaceably mounted in said hollowcylindrically-shaped member and connected to and phase conditions insaid coaxialconductor.

1. A wide-band vertically polarized omnidirectional antenna comprising afirst hollow cylindrically-shaped metal surface divided transversely ofits axis by a circumferentially extending slot into at least two hollowcylindrically-shaped rings having an axial length of 1/4 or 1/2 of thewavelength, three-wire lines distributed uniformly over thecircumference of said first metal surface for feeding said slots, and asecond hollow cylindrically-shaped metal surface arranged within andcoaxially with said first metal surface as a support, wherein theimprovement comprises that said slot is formed of a plurality ofcircumferentially extending individual slots uniformly spaced apart inthe circumferential direction and forming a circumferentially extendinginterrupted ring slot, one said three-wire line for feeding each saidindividual slot, at least one coaxial conductor positioned within saidsecond metal surface, said second metal surface and said coaxialconductor arranged as a coaxial feeder system, said three-wire linecomprising inner wires extending radially inwardly from said first metalsurface, said second metal surface having bores therethrough alignedwith said inner wires so that said inner wires pass contact-free throughsaid second metal surface and are coupled capacitatively or galvanicallywith said coaxial conductor.
 1. A wide-band vertically polarizedomnidirectional antenna comprising a first hollow cylindrically-shapedmetal surface divided transversely of its axis by a circumferentiallyextending slot into at least two hollow cylindrically-shaped ringshaving an axial length of 1/4 or 1/2 of the wavelength, three-wire linesdistributed uniformly over the circumference of said first metal surfacefor feeding said slots, and a second hollow cylindrically-shaped metalsurface arranged within and coaxially with said first metal surface as asupport, wherein the improvement comprises that said slot is formed of aplurality of circumferentially extending individual slots uniformlyspaced apart in the circumferential direction and forming acircumferentially extending interrupted ring slot, one said three-wireline for feeding each said individual slot, at least one coaxialconductor positioned within said second metal surface, said second metalsurface and said coaxial conductor arranged as a coaxial feeder system,said three-wire line comprising inner wires extending radially inwardlyfrom said first metal surface, said second metal surface having borestherethrough aligned with said inner wires so that said inner wires passcontact-free through said second metal surface and are coupledcapacitatively or galvanically with said coaxial conductor.
 2. Awide-band vertically polarized omnidirectional antenna, as set forth inclaim 1, wherein a third hollow cylindrically shaped metal surface ispositioned within said second metal surface, said third metal surfacecomprising one or several coaxial conductors in order to feed theantenna system and, if necessary, comprising also other conductors andfeed lines not used for feeding the antenna system, said second metalsurface and said third metal surface arranged as a coaxial feeder systemof the antenna, said three-wive line comprising inner wires extendingradially inwardly from said first metal surface, said second metalsurface having bores therethrough aligned with said inner wives so thatsaid inner wives pass contact-free through said second metal surface andare coupled capacitatively or galvanically with said third metalsurface.
 3. A wide-band vertically polarized omnidirectional antenna, asset forth in claim 1, wherein said individual slots are rectangular inform.
 4. A wide-band vertically polarized omnidirectional antenna, asset forth in claim 3, wherein a projection on said first hollowcylindrically-shaped metal surface extends into said rectangularlyshaped slot from one side thereof and is spaced from the other sidethereof, and one said inner wire of said three-wire line being coupledwith said projection into said slot.
 5. A wide-band vertically polarizedomnidirectional antenna, as set forth in claim 1, wherein saidindividual slots have conically widening configUration.
 6. A wide-bandvertically polarized omnidirectional antenna, as set forth in claim 1,wherein said individual slots widen in a step-wise manner.
 7. Awide-band vertically polarized omnidirectional antenna, as set forth inclaim 1, wherein said individual slots have a dumbbell-like shape.
 8. Awide-band vertically polarized omnidirectional antenna, as set forth inclaim 7, wherein a projection on said first hollow cylindrically-shypedmetal surface extends into said dumbbell-like shaped slot from one sidethereof and is spaced from the other side thereof, and one said innerwire of said three-wire line being coupled with said projection intosaid slot.
 9. A wide-band vertically polarized omnidirectional antenna,as set forth in claim 1, wherein said first metal surface comprises aplurality of cylindrically-shaped omnidirectional antenna elementsarranged in surface alignment, each said antenna element having an axiallength about equal to half the mean operating wavelength, said antennaelements being spaced apart in the axial direction and forming acontinuous circumferentially extending slot therebetween, and each saidantenna element having said interrupted ring slot therein positionedaxially from and intermediate its opposite ends.
 10. A wide-bandvertically polarized omnidirectional antenna, as set forth in claim 1,wherein said first metal surface comprises a continuous axiallyelongated tubular member having a plurality of axially spaced saidinterrupted ring slots therein dividing said tubular member into aplurality of interconnected omnidirectional antenna elements.
 11. Awide-band vertically polarized omnidirectional antenna, as set forth inclaim 2, wherein at least a part of one of said coaxial conductorscomprises an axially elongated hollow cylinder forming an outerconductor and an axially elongated inner conductor positioned coaxiallywithin and spaced inwardly from said hollow cylinder, said hollowcylinder connected conductively to said third metal surface and saidinner conductor connected conductively to said second metal surface.